In the airline industry, cargo is typically transported inside containers referred to as "unit load devices" which are stowed in cargo holds below the deck of the aircraft. The size and shape of unit load devices vary depending upon the type of aircraft in use. For example, "LD3" unit load devices have a "pallet extension" at one end to conform to the curved sidewalls of the cargo hold compartments of a Boeing 747 or a Macdonnell Douglas DC 10 aircraft (the fuselage of such aircraft is round or oval in cross-section).
Most airlines have a fleet of different types of aircraft. Very often cargo containers shipped to a destination in one type of aircraft cannot be efficiently returned to the place of origin in another type of aircraft due to the different cargo hold configurations. This results in expensive inventory and storage problems. Often large numbers of cargo containers must be repositioned by some other mode of transportation. Since cargo containers are bulky, they are usually disassembled prior to shipment without a load. The containers must then be reassembled at the place of origin before they are reused.
The weight of cargo containers is a significant factor when calculating aircraft fuel burn. The air cargo industry is therefore seeking lighter weight cargo containers to lower operating costs.
Some collapsible cargo containers for aircraft are known in the prior art. For example, U.S. Pat. No. 5,279,437, which issued to Kupersmit on Jan. 18, 1994, relates to a collapsible cargo container for aircraft. In an erected position, the container roof is supported above a pallet base by a plurality of wall panels. One shortcoming of the Kupersmit container is that the wall panels are constructed from a relatively rigid foldable material, such as corrugated fiberboard, plastics or aluminum. Such materials are relatively heavy. Another shortcoming is that the roof is interconnected at its peripheral edges to the wall panels which limits the manner in which the container will collapse.
U.S. Pat. No. 3,578,050, which issued to Weingarten et al. on May 11, 1971, also discloses a collapsible air cargo container. The Weingarten container has a rigid pallet base and flexible walls. The container walls are inflated for supporting the container in an upright, expanded position and are deflated when the container is returned empty to the place of origin without a load. Several knocked-down containers can be shipped in the space ordinarily occupied by a conventional container of the rigid and non-collapsible type. However, a fundamental drawback to the Weingarten design is that the container will not function as intended if the container walls are punctured or torn during cargo handling.
The need has therefore arisen for a light weight, collapsible airline container which overcomes the various limitations of the prior art.